It took 20 minutes for the German liner Steuben to sink with 4,500 souls after Russian torpedoes split its hull in 1945. It took 60 years to find the ship's remains in the Baltic Sea.

Get a taste of what awaits you in print from this compelling excerpt.

The Baltic Sea was as gray as storm clouds when the four of us jumped into the water. We each had several tanks filled with different mixtures of gases for breathing at depths up to 235 feet (71 meters)more than twice as deep as conventional scuba diving. The waves kicked us around as we swam, so when we reached the marker buoy, we submerged as quickly as possible, and the weight of our equipment seemed to lighten.

We were on our way to examine the recently discovered remains of Steuben, a German ship sunk during World War II with the loss of perhaps 4,500 livesthree times the death toll of Titanic. A private Swedish team and later the Polish Navy had both scanned the ghostly wreck with sonar. But only a handful of divers had seen it since it was hit by two torpedoes from a Soviet submarine on February 10, 1945.

By the time we reached 70 feet (20 meters), the sea was as dark as night: Even with our powerful underwater lights we could see nothing but the dive line from the buoy going down. The deeper we went, the gloomier it felt. Finally at 150 feet (45 meters) a huge shape emerged from the darknessdifficult to recognize at first because it was resting on its side. But as we swam closer, I made out the outline of the gracious ship's hull, crowned with an elegant railing and straight rows of portholes.

Built in 1923, Steuben had been converted in 1944 to transport wounded soldiers. Armed with antiaircraft guns, the 550-foot-long (170-meter-long) vessel was jammed with more than 5,000 people, including at least 1,000 civilian refugees, when it was attacked 40 miles (60 kilometers) off the German coast. Only 659 people were rescued from the icy water.

Thoughts of the terrible scenes from 60 years ago rushed through my head as I swam past the promenade deck. I imagined the crowd of people squeezed into the narrow passageways, struggling to reach the stern deck in time to find a raft or a boat. When I peeked inside through the large, smashed windows, what surprised me most was the complete emptiness: no ship equipment, no baggage thrown around, nothing. The power of the water surging through the decks must have been so tremendous that it swept away everything, leaving just naked walls.

Past the promenade deck I saw the entrance to the concert halls that had been packed with wounded German soldiers, and I knew that inside there must be the remains of thousands of them. I remembered what Polish Navy officers had told me after they'd investigated the wreck in late May 2004. They'd taken a good look at the sea bottom with a remotely operated vehicle and found the entire area around the wreck "covered with human remains, skulls, and bones."

We didn't swim into the ship. Not only because it was dangerouswe might get entangled and run out of air before we could get freebut also because we believed this underwater tomb deserved respect. It was easy to imagine the dramas that had taken place here, having heard the stories myself from some of the last living survivors. Despite what the Nazis had done to my country, I had tears in my eyes as I listened.

In More to Explore the National Geographic magazine team shares some of its best sources and other information. Special thanks to the Research Division.

The three largest marine disasters in history were the 1945 Baltic losses of Wilhelm Gustloff, Goya, and Steuben. But how many people were on these ships? Approximately 5,200 people were on Steuben when it set sail on February 9, according to our article, and 4,500 people died when the ship sank. This is based on the eyewitness testimony of Joachim Wedekind, a German merchant marine officer who was on Steuben as a passenger and says he was involved in helping the ship's officers estimate the number of people on board: "I counted 5,200, but we reported only 3,600 or so." Wedekind claims they reported less than were on board because German authorities had forbidden such large evacuations.

Counterbalance that with historian Heinz Schön, who claims that a smaller total is accurate. Schön says Steuben had 2,800 injured soldiers, 800 refugees, 100 returning soldiers, 172 navy hospital crew including doctors and nurses, 12 Red Cross nurses, 64 crew for the ship's anti-aircraft guns, 61 navy seamen, radio operators, signal men, machine operators, and administrators, and 165 navy crewmen, for a total of 4,267 people. Since 659 survivors were counted after Steuben sank, according to Schön, 3,608 died when the ship went down.

Let's compare that to the sinking of Wilhelm Gustloff on January 30, 1945. The Gustloff's records cite 918 naval officers and men, 173 crew, 373 women's naval auxiliary, 162 wounded, and 4,424 refugees, for a total of 6,050 people. In 1980 a trio of British journalists studied the tragedy and reported an estimated 7,000 to 8,000 deaths on board Gustloff. But Schön, a survivor of the Gustloff tragedy, has revised the Gustloff numbers in his more recent works, based on an analysis of the movement of people conducted by a documentary film company. "When it sank," Schön wrote to me, "there were 10,582 passengers on board. 8,956 were refugees, mainly women and children. 9,343 died when the ship sank (it took 62 minutes after the torpedo attack) and 1,239 survived."

And Goya? One of the more reliable reports says 7,000 refugees and wounded soldiers were on board when it departed Hela, near Danzig. When Goya was hit by Soviet torpedoes and sank in four minutes, all except 183 survivors went down with the ship. And until Schön revised his figures in the late 1990s, Goya was reported to be the largest loss of life in maritime history. Now it is the second largest loss. And Steuben remains third.